[GreenKeys] Strange RTTY Signal on 29.684

[Peter Gottlieb]

For someone who is very deep into certain aspects of these incredible 
machines I am about to ask a few very basic questions.

How is the frequency of the signal determined? 
Is it the mark or the space? 
How can you tell on such a signal what is the mark or space?
How did you determine there is a 78 bit autocorrelation?  What software 
did you use?
How about the baud rate?

Over here in NY I find many similar types of signals and had been told 
many times they are encrypted.  Indeed, they are not normal 5 or 8 level 
code as there seems no way to set up to receive without framing errors.  
Unfortunately, every time I find some real solid signal it is one of 
these.  I would love to be able to copy, even if I can't decode.

Peter


John Vendely wrote:
> The FSK signal I mentioned in my earlier reply to Geoff's posting is 
> still present, 24/7, from the direction of Cape Canaveral Air Force 
> Station. Apparently a ground wave system, the signal is quite strong 
> in that vicinity, and fairly weak 35 or so miles down the coast at my 
> QTH.  The exact frequency is 29.824536 Mc, with 100 shift, 82 baud.  
> The signal is not completely random, but shows a 78 bit 
> autocorrelation.  Of course, it's not baudot RTTY in the sense we 
> normally think of, and therefore probably not of burning interest to 
> most of us on this list.  But it's a specialized, narrow-shift, low 
> baud rate FSK signalling system of some interest, especially given the 
> paucity of true RTTY on the air these days.  I have no idea of its 
> purpose, but further statistical analysis might shed some light on 
> this.  It would be interesting to know if Geoff's "mystery" FSK signal 
> shows the same characteristics, indicating the system might be in 
> widespread use, perhaps by the military, or NASA.  Whatever the case, 
> it's an interesting choice of frequency, which probably also has some 
> relationship to its purpose...
>
> 73,
>
> John K9WT
>
>
> ----- Original Message ----- From: "Geoff Fors" <wb6nvh at mbay.net>
> To: <greenkeys at mailman.qth.net>
> Sent: Friday, June 06, 2008 1:53 AM
> Subject: [GreenKeys] Strange RTTY Signal on 29.684
>
>
>> Out here in central California we are picking up a Baudot RTTY signal on
>> 29.684 MHz which runs 24 hours a day, 7 days per week, continuously.  It
>> appears to be encrypted.  It's coming in on ground wave as the signal is
>> about the same strength, day or night.  I haven't taken a look at the 
>> signal
>> yet as far as speed, shift, etc..
>>
>> Anybody have a suggestion what this might be?  10 Meters is an exclusive
>> authorization, not a shared band, so it shouldn't be anything 
>> commercial. I
>> am guessing it's some sort of military use, although how much Baudot 
>> gear
>> would the military still be using these days?
>>
>> Geoff
>> WB6NVH
>>
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